The present inventions relate to sand-control apparatus for use in subterranean wells, and in particular contemplate improved mechanical apparatus for attaching a sand-control screen jacket assembly to a base pipe and methods of using the same.
The control of the movement of sand and gravel into a well bore has been the subject of much importance in the oil production industry. The introduction of sand or gravel into the wellbore commonly occurs under certain well conditions. The introduction of these materials into the well commonly causes problems including plugging and erosion. There have therefore been numerous attempts to prevent the introduction of sand and gravel into the production stream.
A common method to prevent the introduction of sand and gravel into the production stream has been a procedure known as gravel packing. In general, this involves placing a selected sand or gravel into the annular space between the wellbore and a base pipe introduced into the wellbore for that purpose. The base pipe contains perforations designed to allow well fluids to flow into the base pipe while excluding other material. A sand-control screen is commonly used in conjunction with a base pipe. An appropriately sized screen is commonly formed into a jacket and wrapped around the outside of the base pipe to prevent the entry of sand. Exemplary apparatus and methods of connecting a sand-control screen jacket assembly to a base pipe are disclosed in U.S. Pat. No. 5,931,232, which is assigned to this assignee and is incorporated herein for all purposes by this reference thereto.
One method of enhancing production in a well using a sand-control screen jacket assembly includes causing the radial expansion of the base pipe and surrounding screen jacket assembly by drawing a mechanical expansion tool through the base pipe. The radial expansion of the screen jacket assembly and base pipe is known to cause a related shrinkage in the length of both the base pipe and the screen jacket assembly. Since the base pipe is concentrically enclosed by the screen jacket assembly, the mechanical expander deployed in the base pipe necessarily causes greater expansion in the base pipe than in the surrounding screen jacket assembly. Correspondingly, the base pipe undergoes a greater contraction in length relative to the screen jacket assembly. This differential change in length causes problems such as cracking at the junction between the screen jacket assembly and the base pipe and can lead to the introduction of sand and gravel into the production stream.
Due to the aforementioned problems with the introduction of sand and gravel into the production stream, a need exists for apparatus and methods providing a robust mechanical sand-controlling, longitudinally moveable connection between a sand-control screen jacket assembly and a base pipe. Such a connection should withstand downhole production conditions including radial expansion and the related differential longitudinal contraction of the base pipe and sand-control screen jacket assembly.
In general, the inventions provide apparatus and methods for connecting a sand-control screen jacket assembly to a base pipe while providing for longitudinal movement of the screen jacket assembly relative to the base pipe.
The apparatus employs a substantially tubular screen jacket assembly having a first ring affixed to at least one end. A second ring is affixed to the outer surface of the base pipe of the screen jacket assembly wherein the first and second rings have sand-controllingly overlapping portions defining a longitudinally movable joint. The joint has a stop integral with the overlapping portions of the first and second rings, which prevents the possibility of longitudinal separation of the screen shroud and base pipe.
According to one aspect of the invention the stop comprises a plurality of corresponding screws and slots in the respective overlapping portions of the first and second rings.
According to another aspect of the invention, the stop comprises correspondingly opposed surfaces of the respective overlapping portions of the first and second rings.
According to yet another aspect of the invention, the ring affixed to the base pipe is attached by a plurality of fasteners such as set screws.
According to still other aspects of the invention, the screen jacket assembly has one or more longitudinally deformable pleats or slots.
According to another aspect of the invention, the screen jacket assembly has one or more radially expandable pleats.